System International:in 1960, an international committee agree on a contain set of definitions and stranded to explain the physical quantities. A system that accepted and established by all committee members it called SYSTEM INTERNATIONAL.
This system set on three types of unit namely: basic units, supplementary units, derived units.
Base Units:
There are seven units for a various physical quantities, that are length, mass, time temperature, electronic current. luminous intensity and amount of substances (with specialty reference to particles numbers). It called base units.(Table of base units with their symbol are blew).
Supplementary Units:
In General Conference on Weight and Measurement has not yet grouped the certain units of SI under either base units and derived nits. These all SI units called supplementary nits.At that time when grouping of certain units, contain only two units of purely geometrical quantities, which are dived in plane angle and solid angle.
1. Radian:
The radain is the plane angle between two radii (two segments that draw in circle) of a circle which inter-sectioned circumference and arc, equal in length to radius. (as shown below)
2. steradian:
The steradin is angle of solid three-dimensional angle subtended the center point of sphere by its surface area equal to the square of radius of the sphere.
Derived Units:
SI units for measuring all other physical quantities are derived from base units and supplementary units. (in below table derived units )
scientific notaion:
Numbers are explained by stranded form called scientific notation, which use by the powers of ten. As internationally accepted practice is that threre should be only non-zero digits left of decimal. So, the number 144.6 should be written in scientific notaion as 1.446*10^2. There use some prefixes in scientific notation to format a stander measure.
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